The disclosed embodiments of the present invention relate to frame timing control, and more particularly, to a frame timing controller for triggering at least a receiver in a mobile station to start receiving transmitted information of a base station by referring to at least a frame pointer and related frame timing control method thereof.
In orthogonal frequency division multiple access (OFDMA) communication systems (e.g., a WiMAX (Worldwide Interoperability for Microwave Access) system, an LTE (Long Term Evolution) system, etc.), a mobile station (MS) has to simultaneously keep connections with multiple base stations (BS's). These BS's may have different fundamental sampling rates/signal bandwidths, but the frame lengths (or the frame interspacing) of the BS's are identical to each other. Taking the WiMAX system for example, there are five different fundamental sampling rates/signal bandwidths that should be supported by the hardware, and each frame length (or the frame interspacing) for these five different fundamental sampling rates/signal bandwidths is always equal to a fixed value such as 5 miliseconds. For some circumstances, the MS has to switch it's receiving/transmitting target from one BS to another BS. To achieve good connection quality and real-time signal processing, there are many properties of each associated BS that shall be maintained by the MS. One of these critical properties is the frame timing location. One simple way is to allocate one dedicated system timer or counter for each BS, but it brings higher cost which may be proportional to the number of associated BS's with which one MS tends to keep connections.
The other problem arises from the fact that the sampling clock frequency of the MS may be an interference source to either the operating radio frequency (RF) channel of the MS, or other communication systems. The common solution is to change the clock frequency of the MS to avoid the undesired performance degradation. However, as the counting frequency of the system timer/counter of the MS may be coherent with the sampling clock frequency, the change of the sampling clock frequency also changes the counting frequency of the system timer/counter of the MS. The frame timing control must be adjusted or modified for all of the associated BS's correspondingly.
Thus, there is a need for an innovative frame timing control scheme which can control the transmitter/receiver operation in a simple and efficient way.